Endodontics is a field of dentistry which deals with tooth pulp and the tissues surrounding the root of a tooth. Root canal treatment, endodontic retreatment and surgery, treating cracked tooth, and treating dental trauma are some of the endodontic procedures known in the art, of which, root canal treatment is one of the common procedures. Root canal treatments generally involve access to a tooth's root canal, removal of the tooth's pulp that includes the abscessed and dead tissues, disinfecting the root canal, enlarging the root canal, and removing irregularities or rough surfaces within the root canal. Following the root canal treatment, it is necessary to fill and to seal the evacuated root canal in order to prevent further ingress of microorganisms, which lead to recontamination thereof. Thus the pulp tissue and excised portions of the root should be replaced with dental cement or dental filling materials which are biocompatible to living tissues, bio-inert, and so on.
The most common dental filling material that used is Gutta-Percha, which is a natural resin and a thermoplastic rubber. However, the non-adhesive character of Gutta-Percha and the irregularities on the internal surface of the root canal makes it difficult to seal off the root canal completely. In order to overcome this limitation, sealants are used along with Gutta-Percha. An ideal root canal sealant should be biocompatible, anti inflammatory, antibacterial, bio-inert, non-toxic, radiopaque, and exhibit little to no shrinkage or, preferably, even expand slightly for better sealing. An ideal sealant should also have high wetting and low viscosity to seal the space between the filling material and the root canal walls.
Numerous sealants have been known in the art, for example, epoxy, calcium hydroxide, and zinc oxide eugenol-based sealers. During the root canal filling process, such materials are first applied to the Gutta-Percha, which is then inserted into the root canal. Alternatively, they may be inserted using a file or reamer applicator, so that the spaces between the Gutta-Percha points and the root canal walls can be sealed. However, controlling the exact amount of the sealant and/or filling material within the root canal to avoid overextension or overfilling has long been a challenge for endodontists. For example, in case of overflow of root canal sealant from the apical foramen into the periradicular tissue during a root canal filling process, the excess material should be desirably tolerated by the surrounding tissue.
One of the drawbacks of conventional sealants is that they tend to be hydrophobic, making them incompatible with moist tissues within the root canal. Thus the hydrophilic nature of the root canal environment inhibits adequate penetration, complete wetting, and efficient adhesion of the hydrophobic sealant to the root canal walls. As a result, a poor seal is made between the Gutta-Percha and the root canal walls leading to re-entrance of microorganisms into the canal. In addition, overfilled Gutta-Percha and/or conventional sealant materials irritate the periapical soft tissues and do not stimulate healing and hard tissue formation. Moreover and most importantly, Gutta-Percha and conventional sealants degrade during long-term exposure to fluids present in the mouth.
Gutta-Percha and conventional sealants can also be used for root-end fillings, where the function of root-end filling materials is to interrupt all paths between the root canal system and its external surface. The root-end filling material should be antibacterial, nontoxic, noncorrosive, bio-inert, biocompatible, dimensionally stable, easy to handle, radiopaque, cost-effective, adaptable to the dentinal walls, and able to induce regeneration of bone and periodontal attachment. Root-end filling materials typically include Gutta-Percha (as mentioned before), an amalgam, reinforced zinc oxide eugenol cement, such as intermediate restorative material, glass ionomer cement, and/or mineral trioxide aggregate. However, typical root-end filling materials stain soft and hard tissues, leak from corrosion, are dimensionally unstable, are sensitive to moisture, and are expensive. To perform root perforation, the filling material should be able to fill the perforation site effectively and seal the avenue of communication between the oral cavity and the underlying periodontium.
White Mineral Trioxide Aggregate (WMTA) is another one of the commonly used dental cements, which is also used as a root-end filling material. While WMTA has many advantages including biocompatibility, good sealing ability, and antibacterial properties, it suffers from low pH resistance, which affects the microhardness, and long setting time. More particularly, the initial and final setting times of WMTA is about 40 minutes and more than 3 hours respectively, which is not desirable especially when used as a root-end filling material.
Pulp capping is another endodontic procedure, which is aimed at preserving the vitality of the pulp. The materials used for pulp capping must also be biocompatible, bioactive, nontoxic, and should not cause irritation to the pulp. An ideal material should also allow for the regeneration of surrounding tissue and dentine. Calcium hydroxide is a commonly used pulp capping material. However, calcium hydroxide has a very limited working time and is degradable by long-term exposure to tissue fluids that are commonly present in the mouth.
Therefore, in the light of the above discussion, there remains a need for a multi-purpose dental composition for use in root canal treatments, root-end filling procedures, and pulp capping, which nullifies the drawbacks of aforementioned dental materials used for the same.